Eye disorders and vision loss are conditions that often involve extended direct and indirect costs, which are likely to continue to increase with aging populations and contribute to growing healthcare expenditures. Vision loss in adults over the age of forty is attributable to four major ocular diseases: macular degeneration, diabetic retinopathy, glaucoma, and cataract. Macular degeneration and diabetic retinopathy affect the posterior segment of the eye, while glaucoma and cataract affect the anterior segment.
In macular degeneration, the macula of the retina is damaged by the abnormal growth of blood vessels and central, focused vision is damaged. Lack of nutrient supply for macula and ultraviolet exposure are believed to contribute to the progression. Macular degeneration, also known as age-related macular degeneration (AMD), typically occurs in older people, and is one of the leading causes of blindness in the U.S. Diabetic retinopathy is similarly associated with new, abnormal blood vessels bleeding into the retina and vitreous. Therapeutic interventions for posterior segment ocular diseases involving delivery of agents to the posterior of the eye are limited due to the physiological barriers of the eye.